I know it scales off of intellect and spellpower - but how about crit/haste (ratings, from Windsong/Elemental Blast) or Elemental Mastery? And does it still take a snapshot, or does it now update after the spell is cast?
Don't think it would scale with mastery though, if that was the case.
It scales with Enhancement's Mastery; the Fire Elemental's attacks are Fire, and are boosted.
For Elemental, our Overload Mastery only procs if you cast Lightning Bolt or Lava Burst. If the Fire Elemental ever cast either, in theory, he'd have a chance to Overload as well, but since he doesn't, Elemental's Mastery doesn't boost the FET at all.